The primary objective is to evaluate the safety of GSK1605786A, as assessed by recording of adverse events, clinical laboratory parameters, vital signs and electrocardiogram. Secondary objectives will include assessments of effectiveness of long-term treatment with GSK1605786A. Health outcomes assessments will include changes in Inflammatory Bowel Disease Questionnaire (IBDQ), SF-36v2, EQ-5D, Work and Productivity Activity Impairment-Crohn's Disease (WPAI-CD) and disability.